Tryptophan

Tryptophan is an essential amino acid. It is the precursor to 5-hydroxytrypophan (5-HTP) which is the direct precursor to serotonin. Serotonin is important for mood and sleep; when it is deficient, this can lead to anxiety, depression, insomnia, and various other neuropsychological conditions. Tryptophan is the precursor for vitamin B3 in the form of nicotinamide adenine dinucleotide (NAD). Only about 1/60th of the tryptophan in the body is actually converted to NAD. Pellagra, characterized by the 4 D's, dermatitis, diarrhea, dementia, and death, is both a deficiency in vitamin B3 and tryptophan. Because 5-HTP is the direct precursor to serotonin, it has more clinical applicability.

Food Sources

Tryptophan is the least plentiful amino acid found in foods. It is generally deficient in most dietary protein sources. There may be an increase in carcinogenecity in foods which contain tryptophan which have been charboiled or heated to high temperatures.

Uses

Dietary tryptophan as a treatment for stress, insomnia and depression, IHP, May 2008

Depression and Manic-Depressive Mood Swings: Tryptophan is useful with or without other antidepressants such as amine oxidase inhibitors, lithium, and tyrosine. 5-HTP is also useful for treating depression.

Prescribing Considerations

Tryptophan is best taken with a low-protein, carbohydrate-rich meal or snack to decrease risk of gastrointestinal distress. Also insulin response to carbohydrates helps to facilitate tryptophan into the CNS.

No RDA has been established. To determine what your specific requirements are talk to your naturopathic doctor or other trained medical professional.

Safety

General Adverse Effects: anorexia, dizziness, drowsiness, dry mouth, headache, nausea, sexual disinhibition; over the long-term, tryptophan supplementation may increase levels of other amino acids leading to other adverse side effects

Children: Insufficient research to determine any age-related effects of taking tryptophan.

Adults: 7g/150 Ib body weight can lead to gastric irritation, vomiting, head twitching

Seniors: Insufficient research to determine any age-related effects of taking tryptophan.

Pregnancy and Breastfeeding: Well designed human studies showing the effects of tryptophan in pregnant and breastfeeding women do not exist. Animal studies show that 8g/day can be teratogenic. It is not known if L-tryptophan passes into breast milk but there have been no reports of adverse effects on nursing babies. Caution should be used.

Sibutramine and Other Serotonin Agonists - Concomitant use can lead to clinically significant serotonin excess and major risk of serious adverse effects. Avoid concomitant use.

Separate Intake:

Clorazepate - Potential competition between drug and tryptophan may interfere with drug activity.

Other:

Tricyclic Antidepressants - Tryptophan can potentiate the action of TCAs. This additive effect can result in rapid onset of severe symptoms but might also be applied purposefully within a tightly managed therapeutic protocol.

Nutrient Interactions

Large, Neutral Amino Acids:Tyrosine, Phenylalanine, Valine, Leucine, Isoleucine - Tryptophan competes with other large amino acids for transport across the blood-brain barrier. Tryptophan is typically administered between meals, with carbohydrates to facilitate entry through the blood-brain barrier and with vitamin B6, vitamin B3, and vitamin C.